On Tue, Mar 24, 2009 at 11:49:26AM -0700, david@xxxxxxx wrote: > On Tue, 24 Mar 2009, Matt Domsch wrote: > > >You may recall http://lkml.org/lkml/2006/9/29/268, wherein I described > >network device enumeration and naming challenges, and several possible > >fixes. Of these, Fix #1 (fix the PCI device list to be sorted > >breadth-first) has been implemented in the kernel, and Fix #3 (system > >board routing rules) have been implemented on Dell PowerEdge 10G and > >11G servers (11G begin selling RSN). > > > >However, these have not been completely satisfactory. In particular, > >it keeps getting harder and harder to route PCI-Express lanes to > >guarantee the same ordering between a depth-first and breadth-first > >walk, and it turns out, that isn't sufficient anyhow. > > > > > >Problem: Users expect on-motherboard NICs to be named eth0..ethN. This > >can be difficult to achieve. > > I dispute this statement. > > I have several hundred servers that have the on-motherboard NICs as the > last ones. > > anyone who's been making the assumption you describe will have been > running into problems for many years. > > it's just not a valid assumption. I agree it's not a valid assumption. People seem to want two things with names: 1) that devices be named deterministically 2) that the determinism doesn't change on a per-platform or per-configuration-of-a-platform basis. This tends to mean they want the onboard devices named first, then the add-in devices named. But not necessarily. I would hope to have a deterministic naming method that would work for most people by default, but that could be changed (in userspace) as necessary. > >4) When adding a network card to an existing system, what should the > > ports on the new card be named? If it is added, they will be named > > ethN+1... above the existing named cards. This means a (new) > > add-in card in PCI slot 3 may have ports named eth5 and eth6, while > > an add-in card in PCI slot 5 may have ports named eth2 and eth3. > > This is not intuitive. > > this approach causes serious problems in a few cases, including > > 1. a NIC goes bad and you replace it. now all the configs change > > 2. you reinstall a box and it's interface names change. Right. These cases are only deterministic because they start from a known state; change or remove that state, and you're back to non-deterministic. -- Matt Domsch Linux Technology Strategist, Dell Office of the CTO linux.dell.com & www.dell.com/linux -- To unsubscribe from this list: send the line "unsubscribe linux-hotplug" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
